Cigarette making

ABSTRACT

Shredded tobacco is carded by feeding it to a tower down which the tobacco gravitates against an airstream. The tower is formed of opposed walls of zigzag shape. The inner peaks of the zigzags touch planes that converge downwardly and are spaced apart. Tobacco thus falls in countercurrent to an airstream with constantly decreasing velocity and passes successive areas of vortex flow as it gravitates down.

United States Patent 474,354 5/1892 Baker et a1 209/137 895,616 8/1908 Burian 209/137 1,425,801 8/1922 Smith 131/84 UX 1,425,801 8/1922 Smith 131/84 UX 1,753,573 4/1930 Lorentz 131/146 X 1,832,119 11/1931 Hohnetal. 131/110A 2,328,568 9/1943 Maxwell et 31.. 209/136 2,340,914 2/1944 Whitaker 131/21 B 2,989,055 6/1961 Labbe 131/21 A 3,255,763 6/1966 Hadley 131/110 X 3,310,059 3/1967 Grinzinger 131/146 FOREIGN PATENTS 1,244,396 9/1960 France 131/110 Primary Examiner-Joseph S. Reich Anorney-Young & Thompson ABSTRACT: Shredded tobacco is carded by feeding it to a tower down which the tobacco gravitates against an airstream. The tower is formed of opposed walls of zigzag shape. The inner peaks of the zigzags touch planes that converge downwardly and are spaced apart. Tobacco thus falls in countercurrent to an airstream with constantly decreasing velocity and passes successive areas of vortex flow as it gravitates down.

CIGARETTE MAKING This invention relates to cigarette making.

In making cigarettes it is necessary to cut the tobacco into thin strands to form shredded tobacco. The cutting operation is conducted on suitably pretreated tobacco leaves and stems which have been compressed to provide a suitable subject for the cutters. The resulting shredded tobacco is of nonuniform density and is not suitable for making cigarettes without further treatment.

The further treatment consists in a carding operation in which the shredded tobacco is mechanically worked by various devices, some of which may be combs. This may cause damage to the strands.

In U.S. Pat. No. 1,863,666 a process for removing dust from tobacco particles is disclosed. In this process cut tobacco is moved through an airstream which has different speeds in different parts of its path. In other words the air flows through wide and narrow sections. The specification says that the tobacco particles are loosened and that dust is removed in the airstream.

Judging from tests conducted by the applicant, the method disclosed in the above-mentioned U.S. patent does not lead to efficient carding of shredded tobacco, but simply to a loosening up which frees dust. Before the shredded tobacco can be used in cigarette manufacture, a further carding step will have to follow.

An object of the present invention is to utilize an airstream for the carding of tobacco and hence to minimize mechanical damage to the strands of tobacco.

According to the invention the shredded tobacco is caused to fall freely along a path in which the velocity of the gas stream decreases constantly towards the top and the gas stream follows a path in which eddy currents are created to either side of the path of fall of the cut rag.

Preferably the tobacco is caused to fall at a constant mass rate. The term constant mass rate means that the mass of shredded tobacco fed per unit of time remains substantially constant over the period of operation of the apparatus. A device for achieving a constant mass rate is disclosed in copending U.S. Pat. application Ser. No. 823,572, on May 12, 1969, by the same applicant.

Apparatus for carding shredded tobacco comprising a vertical conduit with varying cross-sectional area, means to cause air to rise in the conduit and means to feed cut rag into the top of the conduit is characterized according to the invention by a conduit in which the cross-sectional area increases constantly towards, the top, which has a central clear zone for free fall and pockets to either side of the central zone in which eddy currents may be created.

The conduit may consist in a vertical box with zigzag sides, the peaks of which are in staggered relationship and the inner The invention is further discussed with reference to the accompanying drawing, in which is a schematic view of apparatus according to the invention.

In the drawing there is a box having sidewalls I0 and 11 which are formed to zigzag shape as illustrated. Opposed peaks are staggered and the inner peaks define a downwardly converging channel indicated by the dotted lines 12. The dotted lines converge at an angle of approximately 2%". The convergence has been exaggerated in the drawing for the purpose of clarity.

An inlet 16 is provided to the box.

Below the inlet 16 the walls 10 and 11 are exact replicas of one another, so that except for the distortion introduced by the channel 12 the walls 10 and 11 define a parallel-sided tortuous path. More importantly horizontal cross sections through the box increase constantly in area from the bottom to the top. The increase in area is again due to the distortion introduced by the channel 12.

The lower end of the box is open and discharges into a chute 13 above an extractor belt 14 or several belts side by side. Therefor each belt 14 could be the paper band of a cigarettemaking machine. In other words the box could deposit straight on to the working bed of a cigarette-making machine.

At the top of the box there is a fan 15 which draw in air from the open end of the box.

Shredded tobacco is introduced through the inlet 16. Preferably the shredded tobacco is delivered to the inlet 16 by a device of the kind disclosed in U.S. Pat. application Ser. No. 823,572.

Thus the shredded tobacco enters the inlet 16 at a constant mass rate. It then proceeds down the channel 12 where it encounters the rising stream of air. The eddy currents formed to either side of the channel 12 causes the tobacco to be pulled first to one side and then to the other side so that finally a unifonnly carded product lands in the chute I3.

I claim:

I. In apparatus for carding shredded tobacco comprising a vertical conduit with varying cross-sectional area, means to cause air to rise in the conduit and means to feed tobacco into the top of the conduit whereby the tobacco falls down through the conduit, the improvements of a conduit the cross-sectional area of which increases constantly towards the top to provide a downwardly tapering free fall zone for falling tobacco, and means providing recesses in the sides of the conduit and opening into the tapering zone.

2. The apparatus claimed in claim 1 in which the conduit consists of a vertical box with zigzag sides having transversely inner and outer peaks which are in axially staggered relationship, the inner peaks being spaced apart the width of the tapering zone. 

1. In apparatus for carding shredded tobacco comprising a vertical conduit with varying cross-sectional area, means to cause air to rise in the conduit and means to feed tobacco into the top of the conduit whereby the tobacco falls down through the conduit, the improvement of a conduit the cross-sectional area of which increases constantly towards the top to provide a downwardly tapering free fall zone for falling tobacco, and means providing recesses in the sides of the conduit and opening into the tapering zone.
 2. The apparatus claimed in claim 1 in which the conduit consists of a vertical box with zigzag sides having transversely inner and outer peaks which are in axially staggered relationship, the inner peaks being spaced apart the width of the tapering zone. 